A bellows pump has a structure in which a bellows divides an enclosed region into a pump chamber and an operation chamber. Then the bellows pump operates to compress and extend the pump chamber by introducing and discharging a working fluid into and from the operation chamber. Known examples of such a bellows pump are, for example, those disclosed in Patent Document 1 and Patent Document 2 listed below.
The bellows pumps disclosed in Patent Document 1 and Patent Document 2 have a configuration in which the bellows has an optimized shape to reduce a problem, such as deformation of a bellows 100 shown in FIG. 4 due to stress concentration caused by an operating pressure as shown by the arrows in FIG. 4. The bellows deformation arises if the pressure exceeds the limit of the bellows' pressure resistance performance or the temperature of the bellows increases too high. The problem has been addressed, therefore, by increasing the pressure resistance by changing the bellows shape as described above or increasing the bellows' wall thickness.